Big Bang Nucleosynthesis in the Post‐WMAP Era

An overview of the standard model of big bang nucleosynthesis (BBN) in the post‐WMAP era is presented. With the value of the baryon‐to‐photon ratio determined to relatively high precision by WMAP, standard BBN no longer has any free parameters. In this context, the theoretical prediction for the abundances of D, ³He, ⁴He, and ⁷Li is discussed. The observational determination of the light nuclides is also discussed. While, the D and ⁴He observations are concordant with BBN predictions, ⁷Li remains discrepant with the CMB‐preferred baryon density and possible explanations are reviewed. Finally, moving beyond the standard model, primordial nucleosynthesis constraints on early universe and particle physics are also briefly discussed.